• Simon Peyton Jones's avatar
    Do not bind coercion variables in SpecConstr rules · fb050a33
    Simon Peyton Jones authored
    Trac #14270 showed that SpecConstr could cause nasty Lint failures
    if it generates a RULE that binds coercion varables.  See
     * Note [SpecConstr and casts], and
     * the test simplCore/should_compile/T14270.
    This doesn't feel like the final word to me, because somehow the
    specialisation "ought" to work.  So I left in a debug WARN to yell if
    the new check acutally fires.
    Meanwhile, it stops the erroneous specialisation.
    binding coercion
T14270a.hs 704 Bytes